Thank you so much! These replies have all been very helpful, and I think I’ve solved the issue!
It was indeed the tension. I almost didn’t even try to fix it because it seems like every time I adjust the tension I make things worse. A huge thank you goes out to those of you who gave me very specific and detailed things to try. I actually learned a lot this afternoon about tension and hopefully I won’t have as many issues in the future. Tension has always been my Achilles’ heel!
There was indeed a hole in the bobbin casing arm that I had never noticed before. That actually helped me out a lot! Also, upon carefully studying my thread path, I noticed that my thread seemed to be snagging a bit on the hook that fed into the tension disc. it always wanted to get looped around.
I also increased the tension on the bobbin case a little bit, although this was a bit of a last resort. For me, my biggest tension issues have always come after I tried to adjust the bobbin. For some reason, that always ends up blowing up in my face. Not this time!
Again, huge, thanks to all of you. You have saved my project!